Read here. Using sediment cores from multiple Elk Island National Park ponds in Alberta, Canada, researchers find that pollen and charcoal records clearly show that these area were warmer and drier during Medieval Warming versus present day conditions. (click on image for different, zoomed view)
"since their...data indicate that sediment charcoal concentrations have not yet dropped to the level characteristic of the MWP -- even with what they describe as the help of "active fire suppression in the park combined with what may be thought of as unintentional fire suppression due to agricultural activity around the park" -- it would appear that their study sites and their surroundings have not yet attained the level of warmth and dryness they experienced during the MWP, which they describe as having occurred over the period AD 800-1200."